1. Field of the Invention
This invention relates to a metal seal.
2. Description of the Related Art
Conventionally, a metal seal for sealing two parallel flat faces, of which cross-sectional configuration is U-shaped and whole configuration is circular, is known (refer to Japanese Provisional Publication No. 2009-24838).
When the above-mentioned conventional metal seal is made non-circular as a whole and disposed along a window portion (opening portion) non-circular as a whole to seal the periphery of the non-circular window portion, total sealing ability may be decreased.
Especially, in case of non-circular having an R-shaped curved portion of extremely small radius of curvature, sufficient sealing ability (tight sealing ability) may not be obtained on remaining straight portions.
It is therefore an object of the present invention to provide a metal seal which shows a uniform sealing ability on the whole periphery.